String puller for string instruments

ABSTRACT

A string puller for selectively adjusting the pitch of the string(s) of a stringed musical instrument. Each string of the instrument is attached to a respective string puller. Each string puller comprises a pivoting member rotatably mounted on a pivot at a pivot support on the pivoting member. The pivoting member has a knife-edge surface which supports the string such that contact of the string at a first end of the scale ends at said knife-edge surface throughout a normal range of pivoting of said pivoting member. The pivoting member is disposed on a lever for pivoting the pivoting member to adjust the tension on the string.

FIELD OF THE INVENTION

The field of the invention generally relates to stringed musicalinstruments, and more particularly to a device for selectively adjustingthe tension (and therefore pitch) of the strings of such musicalinstruments while the instrument is being played.

BACKGROUND OF THE INVENTION

In the past, various pitch adjusting mechanisms for stringed musicalinstruments have been provided. These pitch adjusting mechanismsgenerally operate by selectively increasing or decreasing the tension orpitch of a string by moving one of the secured ends of the string toeither increase the tension (to raise the pitch) or decrease the tension(to lower the pitch).

These types of pitch adjusting mechanisms have found widespreadapplication on steel guitars. In general, a steel guitar is a generallyhorizontally mounted guitar having a head end and a tail end and aplurality of strings extending therebetween. The head end is providedwith a plurality of tuning keys (one for each string) to which one endof a string is secured. The tuning keys allow adjustment of the pitch ofeach string to tune the guitar. The other end of the string is securedto a bridge at the tail end of the guitar.

Typical examples of pitch adjusting mechanisms for string instruments,such as a steel guitar, are found in U.S. Pat. No. 3,688,631 and U.S.Pat. No. 3,390,600. These patents are expressly incorporated byreference herein in their entireties. Each of these patents discloses apitch adjusting mechanism for adjusting the pitch of an individualstring both upwardly or downwardly. The mechanisms in both of these twopatents also have in common that the pitch adjusting mechanism isprovided at the bridge end of the strings and the mechanisms compriserelatively complicated systems of levers, springs and linkages. In orderto provide for both raising and lowering the pitch of the string with asingle lever attached to the string, the mechanisms must provide for asystem which allows the single lever to be selectively actuated in bothdirections, i.e. clockwise and counter-clockwise, and also provide ameans for returning the string to the open tune position (this means thenormal pitch of the string without actuation of the pitch adjustingmechanism) upon de-actuation. Accordingly, the springs and lever arms ofeach of the parts of these mechanisms must be delicately balanced toprovide proper operation and to minimize or avoid mis-tuning.

Therefore, there is need for a pitch adjustment device for stringedinstruments which overcomes the problems associated with prior devices.

SUMMARY OF THE INVENTION

The present invention comprises a pitch adjustment device forselectively adjusting the pitch of the string(s) of a stringed musicalinstrument. Simply stated, in one aspect of the invention, the pitchadjustment device comprises mounting a tuning key for a string on apivotable lever. The tuning key comprises a tuning shaft to which thestring is secured and around which the string is wound. As with astandard guitar, the open tuning of the string (i.e., with the lever inthe “normal position”) can be adjusted by adjusting the tuning key usingan adjustment member, such as a knob, screw head or bolt head.Adjustment of the tuning key causes the tuning shaft to rotate to adjustthe tension on the string, independent of the pivoting of the lever.

The selective adjustment of the tension, or pitch, of the string isattained by pivoting the lever. Specifically, pivoting of the levercauses the tuning key to pivot which changes the tension on the string,while at the same time, the rotational position of the tuning shaftrelative to the lever remains unchanged. In this way, the open tuning ofthe string will be maintained when the lever is returned to the normalposition.

In another aspect of the present invention, an innovative string supportfor stringed instruments is provided. The string support design takesadvantage of the fact that a string produces a better, more resonantsound if there is less contact between the string and its supports (suchas the bridge and the nut of a guitar) defining the scale of the string.The scale is simply the length of the string that resonates to producethe pitch of the string. On a guitar, the scale is defined by the lengthfrom the nut to the bridge. The string support also provides foradjustment to account for the movement of the string caused by theselective pitch adjustment device. Bear in mind that when the selectivepitch adjustment device of the present invention is actuated, the stringwill move slightly in the axial direction of the string (in onedirection for raising the pitch and in the opposite direction forlowering the pitch).

Thus, the string support of the present invention comprises a pivotingmember which pivots in a plane which is substantially parallel to theaxial direction. A knife-edge surface is provided on the pivoting membersuch that the knife-edge surface pivots along with the pivoting of thepivoting member. The knife-edge surface is configured such that the onlycontact of the string between the scale is with the knife-edge surfacethroughout the normal range of pivoting of the pivoting member. Theknife-edge surface provides for the optimum string sound and resonanceand the pivoting action allows the knife-edge to move along with thestring movement when the pitch adjustment device is actuated.

Additional aspects and features of the pitch adjustment device andrelated mechanisms of the present invention will become apparent fromthe drawings and detailed description provided below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side perspective view of an exemplary steel guitar havingthe pitch adjustment device of the present invention.

FIG. 2 is partial top perspective view of a pitch adjustment deviceaccording to the present invention, shown for two strings of the steelguitar of FIG. 1.

FIG. 2A is an enlarged, side view of the roller nut shown in FIG. 2.

FIG. 3 is partial bottom perspective view of a pitch adjustment deviceaccording to the present invention, shown for two strings of the steelguitar of FIG. 1.

FIG. 4 is a partial side of a pitch adjustment device according to thepresent invention, shown for two strings of the steel guitar of FIG. 1.

FIG. 5 is partial side perspective view of a pitch adjustment deviceaccording to the present invention, shown for two strings of the steelguitar of FIG. 1, with a first pitch adjustment device in the actuatedposition.

FIG. 6 is partial side perspective view of a pitch adjustment deviceaccording to the present invention, shown for two strings of the steelguitar of FIG. 1, with a second pitch adjustment device in an actuatedposition.

FIG. 7 is partial side perspective view of a pitch adjustment deviceaccording to the present invention, shown for two strings of the steelguitar of FIG. 1, with a second pitch adjustment device in an actuatedposition.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, the pitch adjustment device 100 of the presentinvention will be described in connection with an exemplary instrument,in this case a steel guitar 10. It should be understood that the pitchadjustment device 100 and other related features are not limited to asteel guitar 10 as shown and described, but can be applied to anystringed instrument. Therefore, the present invention is not limited tothe embodiment on a steel guitar. Moreover, although the steel guitar 10is shown with a single neck, it is common for steel guitars to have twonecks, a front neck and a rear neck, as shown in U.S. Pat. No.3,688,631. It should be understood that the present invention can easilybe applied to both necks of a dual neck steel guitar.

The steel guitar 10 comprises a frame 12 having a head end 13 and a tailend 15. A plurality of strings (in this example, the guitar 10 has 10strings) generally indicated at 19. The head end of each string 19passes over a first string support 20 and then is operatively coupled toa first pitch adjustment device 100 which is attached to the head end 13of the frame 12. The tail end of each string 19 is operatively coupledto a second pitch adjustment device 200 which is attached to the tailend 15 of the frame 12. There is a first pitch adjustment device 100 anda second pitch adjustment device 200 for each of the strings 19. All ofthe first pitch adjustment devices 100 and second pitch adjustmentdevices 200 are substantially identical for each string, and thereforeit is sufficient to describe these assemblies for just one of thestrings 19, although assemblies for two strings are shown in FIGS. 2-7.The assemblies for the other strings are substantially identical, exceptthat the location of some components will vary in order to accommodateeach of the assemblies for each of the strings. For example, as can beseen in FIG. 1, the location of each of the first pitch adjustmentdevice 100 varies so that all 10 devices 100 can fit on the head end 13of the guitar 10.

Referring now to FIGS. 2-7, the first pitch adjustment device 100comprises a pivotable lever 102 pivotally coupled to a key frame 110which is fixed to the head end 13 of the frame 12. The pivotable lever102 pivots about an axis, which in the embodiment of FIG. 3, comprises atuning shaft 114 of a tuning key 112. The axis of rotation of thepivotable lever 102 does not have to be the tuning shaft 114. Forexample, a separate pivot point spaced apart from the tuning shaft 114can be provided using a rod or other suitable device for rotatablycoupling the lever 102 to the head end 13 of the frame 12. In such case,the entire key frame 110 is not fixed to the frame 12 but is insteadattached to the lever 10 such that the entire key frame 110 pivots alongwith the lever 102.

The tuning key 112 is attached to the upper end of the lever 102 and thelower end of the lever 102 passes through an aperture in the frame 12. Afirst end 106 of a pull rod 104 is operably coupled to the lower end ofthe lever 102. The second end 108 of the pull rod is operably coupled toan actuation apparatus 109 (see FIG. 1). The actuation apparatus maycomprise a system of rocking assemblies and/or pedals such as thosedescribed in U.S. Pat. No. 3,688,631 for moving the pull rod 104 axiallyto the right (to pivot the lever 102 in the counter-clockwise direction)and to the left (to pivot the lever 102 in the clockwise direction). Theactuation apparatus may bias the pull rod 104 in a first direction(either left or right) to the normal position (de-actuated ornon-actuated position) and then move the pull rod 104 in the oppositedirection to the actuated position. The normal position versus theactuated position of the pull rod 104 and the lever 102, and thedirection of movement for actuation (right or left for the pull rod 104,counter-clockwise or clockwise for the lever 102), will be reverseddepending on the desired result of actuation (i.e. raising the pitch orlowering the pitch of the string 19). In the configuration as shown inFIGS. 2-7, moving the pull rod 104 to the left rotates the lever 102clockwise, thereby lowering the tension and pitch of the string 19.Moving the pull rod 104 to the right rotates the lever 102counter-clockwise thereby raising the tension and pitch on the string19.

A forward stop 20 is provided on the frame 12 which limits the movementof the lever 102 in the counter-clockwise direction. In the embodimentshown in the figures, the forward stop 20 is simply the right edge ofthe aperture in the frame 12 through which the lever 102 passes. Theforward stop 20 may be fixed or it may be adjustable, such as byproviding an adjustable screw or bolt which is placed to limit themovement of the lever 102 in the counter-clockwise direction. Anadjustable second stop 22 is provided on the key frame 110 to limit therotation of the lever 102 in the clockwise direction. The second stop 22comprises a screw which can be adjusted to adjust the position of thesecond stop 22.

The tuning key 112 comprises the tuning shaft 114 and an adjustmentmember 116 operably coupled to the tuning shaft 114. The tuning key 112is operably connected to the key frame 110 by rotatably coupling thetuning shaft 114 to the key frame 110 so that the tuning shaft 114 mayrotate relatively freely relative to the key frame 110. This may beaccomplished by simply inserting the tuning shaft 114 through anaperture in the key frame 110 and using a screw, rivet or other suitablefastener to retain the tuning shaft 114 in the aperture of the key frame110. The tuning shaft 114 and aperture in the key frame 110 are properlysized to allow the tuning shaft 114 to rotate within the aperture. Thehead end of the string 19 is secured to the tuning shaft 114 of thetuning key 112 by inserting the end of the string 19 through atransverse hole in the tuning shaft 114, and then a portion of thestring 19 is wound around the tuning shaft 114.

As with a standard guitar, the tuning key 112 is used to tune the string19 (for example, in the open tuned pitch) by rotating the tuning shaft114 of the tuning key 112 to adjust the tension of the string 119thereby adjusting the pitch. The adjustment member allows adjustment ofthe tuning key 112 by rotating the tuning shaft 114. The tuningadjustment accomplished using the adjustment member 116 is independentof the pitch adjustment provide by pivoting the pivotable lever 102, asdescribed below. In other words, the adjustment member 116 rotates thetuning shaft 114 while the pivotable lever 102 remains stationary. Theadjustment member 116 may be a structure provided on the tuning shaft114, such as a knob for allowing manual adjustment, or a screw head orhex head for receiving a tuning tool such as a screw driver or wrench,or other suitable device. Or, as shown in FIG. 3, the adjustment device116 may comprise a worm gear 118 having a knob 120. The worm gear 118 isrotatably coupled to a bracket 124. The worm gear 118 couples to amating gear 122 provided on the tuning shaft 114. The bracket 124 issecured to the lever 102. In order to retain the proper tension andpitch on the string 19, the tuning key 112 should have a retainingdevice for preventing the tuning shaft 114 from unintentional rotation.If not retained in a tuned position, there can be unintended andunwanted rotation of tuning shaft 114 causing the string 19 to go out ofproper tune. The retaining device may simply be a frictional fit betweenthe tuning shaft and an aperture of a bracket through which is passes.In the embodiment of FIGS. 2-7, the worm gear 118 functions as both theadjustment device for the tuning shaft 114 and as a retaining devicebecause a worm gear as configured will inherently resist rotation inresponse to the torque on the mating gear 122 created by the tension ofthe string 19.

The tuning key 112 is mounted on the pivotable lever 102 such thatpivoting the lever 102 causes the tuning key 112 to pivot therebyadjusting the tension on the string 19 while the rotational position ofthe tuning shaft 114 relative to the lever 102 remains unchanged. Saidanother way, when the pivotable lever 102 is pivoted, the entire tuningkey 112 pivots such that the string tension changes, but the tuningposition of the tuning key 112 itself remains unchanged so that when thelever 102 is returned to the normal position, the pitch of the stringreturns to the open tune pitch.

The operation of the pitch adjusting mechanism 100 is fairlystraightforward. As discussed above, the pitch adjusting mechanism 100can be configured for raising or for lowering the pitch of the string 19from the normal position (i.e. open tune position of the string 19).Assuming that the position of the mechanism 100 as shown in FIG. 4 isthe normal, or open pitch position, the mechanism 100 is configured tolower the string pitch upon actuation when moved to the position shownin FIG. 5. The actuation apparatus is configured to bias the lever 102against the forward stop 20. The pitch adjusting mechanism 100 is thenactuated by operating the actuation apparatus which moves the pull rod104 to the left as shown in FIG. 5. The pull rod 104 pushes the lever102, thereby pivoting the lever 102 and the tuning key 112 in aclockwise direction. The clockwise rotation of the tuning key 112rotates the tuning shaft 114 in a clockwise direction thereby reducingthe tension on the string and lowering the string pitch. However, thetuning key 112 and tuning shaft 114 do not rotate relative to the lever.The lever 102 stops when the limit of the second stop 22 is reached.Still, the tension and pitch of the string 19 is lowered by thismovement. When the actuation apparatus is released (or reversed if notbiased to the normal position), the pull rod 104 moves to the right andthe lever 102 and tuning key 112 pivot in a counter-clockwise directionback to the position shown in FIG. 4, thereby raising the tension andpitch of the string 19. When the lever 102 returns to the normalposition set by the forward stop 20, the string will have returned tothe original open pitch because the rotational position of the tuningshaft 114 relative to the lever 102 was not changed by the pivoting ofthe lever 102 and tuning key 112.

In the configuration where the axis of the lever 102 is not coaxial tothe axis of the tuning shaft 114, the operation of the pitch adjustmentmechanism 100 is the same as described above, except that the movementof some of the components differs slightly. The pivoting of the lever102 pivots the tuning key 112 such that the tuning shaft 114 revolvesaround the axis of the lever 102 rather than purely rotating asdescribed above. Still, such motion of the tuning key 112 (and itstuning shaft 114) changes the tension and thus, the pitch of the string.Moreover, since the rotational position of the tuning key 112 and tuningshaft 114 relative to the lever 102 do not change upon the pivoting ofthe lever 102. Thus, upon return of the lever 102 to the normalposition, the open pitch of the string 19 is maintained.

To configure the pitch adjusting mechanism 100 to raise the pitch of thestring 19 when actuated from the normal position to the actuatedposition, simply reverse the normal position and actuated position, andreverse the direction of movement of the moving parts.

The pitch adjusting mechanism may further comprise a bridge nut 130(string support) which defines the head end of the scale of the string130, similar to the nut on a standard guitar. The bridge nut 130 of thepresent invention comprises a nut housing 131, a pivot 134 coupled tothe housing 131 and a rolling nut 132 pivotally mounted on the pivot134. The pivot 134 may comprise a rod 135 received in an aperture of therolling nut 132 such that the rolling nut 132 may pivot about the rod.The rolling nut 132 preferably pivots in a plane which is substantiallyparallel to the axial direction of the string 19. The nut housing 131and/or pivot 134 may receive all or several of the rolling nuts 132 foreach string, or there may be a separate nut housing 131 and/or pivot 134for each string 19.

As best shown in the enlarged view of FIG. 2A, the rolling nut 132 is aplate-like structure having circumferential surface 136. Thecircumferential surface has a curved portion 138 and a knife-edgesurface 140 which is formed by a sharp ledge extending radially inwardfrom the curved portion 138. The rolling nut 132 is oriented such thatthe end point of the contact of the rolling nut 132 with the string atthe head end of the scale of the string is the knife-edge surface 140.The rolling nut 132 pivots about the pivot 134 to maintain the contactof the knife-edge surface 140 at the substantially the same point on thestring 19 when the string 19 moves in response to actuation of the pitchadjusting mechanism 100. A return stop 142 is provided to limit therotation of the rolling nut 132. The knife-edge surface 140 provides forthe optimum string sound and resonance. The pivoting action prevents, orat least minimizes, unwanted squeaking of the string that can occur ifthe string 19 were to slide on the knife-edge surface 140 when thestring moves in response to actuation of the pitch adjustment device100.

Turning now to the tail end 15 of the guitar 10, the second pitchadjustment device 200 will be described. The second pitch adjustmentdevice 200 comprises a bridge mount 202 which is attached to the tailend 15. A string puller 204 is attached to the bridge mount 202. Thestring puller 204 comprises a housing 206 having a mounting lug 208 anda pair of opposing plates 210 extending from the mounting lug 208. Theopposing plates 210 have three sets of coaxial apertures 216, 217 and218 vertically spaced apart. The upper end of a puller lever 212 isreceived between the plates 210 and is pivotally mounted on a pivot 214.The pivot 214 comprises a rod which is received in one of the sets ofapertures 216, 217 or 218. In FIGS. 2-5, the pivot 214 is set in theaperture 218 and in FIG. 7 the pivot 214 is set in the aperture 216.

The upper end of the puller lever 212 comprises a circumferentialsurface 220, very similar to the circumferential surface 136 of therolling nut 132 (see FIGS. 4-7). The circumferential surface 220 has acurved portion 222 and a knife-edge surface 224 which is formed by asharp ledge extending radially inward from the curved portion 222. Theknife-edge surface 224 is oriented such that the end point of thecontact of the rolling nut circumferential surface 220 with the string19 at the tail end of the scale of the string 19 is the knife-edgesurface 224. In addition, through the normal pivoting of the pullerlever 212, the end point of contact of the string 19 is the knife-edgesurface 224. A string attachment 221 is also provided on the lever 212for securing the tail end of the string 19 to the lever 212. The stringattachment 221 can comprise a fitting have a grooved head for loopingthe string 19 around or any other suitable structure for securing thestring 19. The string 19 extends from the string attachment 221, andover the circumferential surface 220 to the knife-edge surface 224.

The three sets of apertures 216, 217 and 218, allows a choice for theradius of the lever arm between the pivot 214 and the tension of thestring on the circumferential surface 220. For example, apertures 216provide the smallest lever arm (for example ¼″) which would be mostappropriate for the string 19 having the least amount of tension. Thisis true because this string applies the least force which must beovercome to pivot the puller lever 212. The apertures 217 provide amedium lever arm (for example 5/16″) which may be suitable for themiddle strings. And the apertures 218 provide the largest lever arm (forexample ⅜″) which is most appropriate for the strings having thegreatest tension. By utilizing differing radii for the pivoting of theupper end of the puller lever 212, the amount of force required toactuate the respective puller levers 212 for each string can be mademore uniform. Thus, if the levers 212 are operably coupled to footpedals, for example, the force required by the musician to push thepedals coupled to their respective strings can be to some extentmatched. FIG. 6 shows the motion of puller lever 212 with the pivot 214located in the middle aperture 217, while FIG. 7 shows the motion of thepuller lever 212 with the pivot located in the lower aperture 217.

The lower end of the puller lever 212 extends through an aperture in thetail end 15 of the frame 12. A forward stop 226 is provided which limitsthe movement of the lever 212 in the clockwise direction and anadjustable second stop 228 is provided to limit the rotation of thelever 212 in the counter-clockwise direction. The second stop 228comprises a screw which can be adjusted to adjust the position of thesecond stop 228.

A first end 236 of a pull rod 234 is operably coupled to the lower endof the lever 212. The lower end of the lever 212 may have a plurality ofvertically spaced apart positions for coupling the pull rod 234 in orderto provide varying lever arms for the same reasons described above. Thesecond end 238 of the pull rod is operably coupled to an actuationapparatus (not shown). The actuation apparatus may comprise a system ofrocking assemblies and/or pedals such as those described in U.S. Pat.No. 3,688,631 for moving the pull rod 234 axially to the right (to pivotthe lever 102 in the counter-clockwise direction) and to the left (topivot the lever 102 in the clockwise direction). The actuation apparatusmay bias the pull rod 234 in a first direction (either left or right) tothe normal position (de-actuated or non-actuated position) and then movethe pull rod 234 in the opposite direction to the actuated position. Thenormal position versus the actuated position of the pull rod 104 and thelever 212, and the direction of movement for actuation (right or leftfor the pull rod 234, counter-clockwise or clockwise for the lever 212),will be reversed depending on the desired result of actuation (i.e.raising the pitch or lowering the pitch of the string 19). In theconfiguration as shown in FIG. 3, moving the pull rod 234 to the leftrotates the lever 212 clockwise, thereby raising the tension and pitchof the string 19. Moving the pull rod 234 to the right rotates the lever212 counter-clockwise thereby lowering the tension and pitch on thestring 19.

The operation of the second pitch adjusting mechanism 200 is similar tothe operation of the first pitch adjusting mechanism 100. As with thefirst pitch adjusting mechanism, the second pitch adjusting mechanism200 can be configured for raising or for lowering the pitch of thestring 19 from the normal position (i.e. open tune position of thestring 19). Assuming that the position of the mechanism 200 as shown inthe solid lines of FIGS. 6-7 is the normal, or open pitch position, themechanism 200 is configured to raise the string pitch upon actuation.The actuation apparatus would typically be configured to bias the lever212 against the second stop 228. The pitch adjusting mechanism 200 isthen actuated by operating the actuation apparatus (not shown) whichmoves the pull rod 234 to the left. The pull rod 234 pulls the lever212, thereby pivoting the lever 212 in a clockwise direction (as shownby the arrows in FIG. 6-7) to the position shown by the phantom lines inFIGS. 6-7. The clockwise rotation of the lever 212 increases the tensionon the string 19 and raises the string pitch. The lever 212 is stoppedwhen the limit of the forward stop 226 is reached. When the actuationapparatus is released (or reversed if not biased to the normalposition), the pull rod 234 moves to the right and the lever 212 pivotsin a counter-clockwise direction thereby lowering the tension and pitchof the string 19. When the lever 212 returns to the normal position setby the second stop 228, the string 19 will have returned to the originalopen pitch.

To configure the second pitch adjusting mechanism 200 to lower the pitchof the string 19 when actuated from the normal position to the actuatedposition, simply reverse the normal position and actuated position, andreverse the direction of movement of the moving parts.

As shown in FIGS. 2-7, and described above, each string has a firstpitch adjusting mechanism 100 at its head end and a second pitchadjusting mechanism 200 at its tail end. It is preferably to configurethe first and second pitch adjusting mechanism 100 and 200, such thatone of the mechanisms raises the string pitch upon actuation and theother mechanism lowers the pitch upon actuation.

While embodiments of the present invention have been shown anddescribed, various modifications may be made without departing from thescope of the present invention. The invention, therefore, should not belimited, except to the following claims, and their equivalents.

1. A string puller for adjusting the tension of a string of a stringedmusical instrument, the string extending in an axial direction, thestring support comprising: a pivoting member rotatably mounted on apivot at a pivot support on said pivoting member such that said pivotingmember pivots about said pivot in a plane which is substantiallyparallel to the axial direction; a knife-edge surface provided on saidpivoting member wherein said knife-edge pivots along with the pivotingof said pivoting member such that contact of the string at a first endof the scale ends at said knife-edge surface throughout a normal rangeof pivoting of said pivoting member; a string attachment for attachingthe string to said string puller; and a lever for pivoting said pivotingmember to adjust the tension on the string.
 2. The string puller ofclaim 1, wherein said knife-edge surface has a string contact length ofless than 500 micrometers.
 3. The string puller of claim 1, wherein saidknife-edge has a string contact length of less than 250 micrometers. 4.The string puller of claim 1, wherein said pivoting member comprises aplate having an axis of rotation about which said plate may rotate, saidplate having an outer circumferential surface which comprises a curvedportion and said knife-edge surface formed by a sharp ledge extendingradially inward from said curved portion.
 5. The string puller of claim4, wherein said axis of rotation of said plate is eccentrically placedrelative to the curved portion of said outer circumferential surface. 6.The string puller of claim 4, wherein said plate comprises a return stopwhich limits rotation of said plate in a first direction.
 7. The stringpuller of claim 1, wherein said string puller is configured to beutilized on the bridge end of the musical instrument.
 8. The stringpuller of claim 1, wherein said pivot support comprises an aperture insaid pivoting member and said pivot comprises a rod received in saidaperture.
 9. The string puller of claim 1, wherein said pivoting membercomprises a plurality of pivot supports at spaced apart locations onsaid pivoting member such that each pivot support is a differentdistance from said knife-edge surface, wherein said pivoting member canbe mounted on one of said pivot supports.